Date: 1661

"What difference is there 'twixt a man and beast, / (None sure at all, or little to be guest) / If't wan't for Reason, and an immortal spark, / Which hides it self within his hollow Ark?"

— Pordage, Samuel (bap. 1633, d. c. 1691)

Date: w. 1755, 1777

"But admitting a spiritual substance to be dispersed throughout the universe, like the ethereal fire of the Stoics, and to be the only inherent subject of thought, we have reason to conclude from analogy, that nature uses it after the same manner she does the other substance, matter."

— Hume, David (1711-1776)